Former world chess champion Bobby Fischer has one day left to file an appeal with Japan's justice minister over his detention. He has been in custody for two weeks after being detained by Japanese immigration officials when he attempted to fly out of Japan with an invalid American passport.

Bobby Fischer was at a Tokyo area airport two weeks ago, planning to leave for the Philippines when he was detained for allegedly violating Japanese immigration law. Mr. Fischer was traveling on an American passport that U.S. officials said had been revoked.

Japanese immigration authorities have turned down his appeal against deportation. Mr. Fischer faces charges in the United States for violating economic sanctions against the former Yugoslavia. He defied international sanctions by playing a chess match there in 1992 against rival Boris Spassky.

Supporters of Bobby Fischer have formed an ad hoc committee to champion his cause. They say Mr. Fischer's U.S. passport was improperly revoked and they argue he should be released or allowed to travel to a third country.

John Bosnitch, who heads the support group, says the fight to free Mr. Fischer is far from over. "Bobby seems to be saying he's going to fight this and expose the way they've been treating him and I think he's in a winning position," he said. Prominent Japanese politician and ardent chess player, Ichiji Ishii, says he is willing to act as Mr. Fischer's legal guarantor, if that will secure his provisional release.

"Because I thought he has no risk of hiding himself. Not only that he has no risk of disappearance himself. So I am going to guarantee in case he is released," he said.

There has been no indication from Japanese or American authorities whether the United States has requested Mr. Fischer's extradition.

Supporters say they are trying to help secure a German passport for Mr. Fischer, based on the fact that his late father was a German citizen.

A spokesman for the German Embassy in Tokyo says it is unclear whether Mr. Fischer qualifies for German citizenship.

Bobby Fischer has until Friday to make a plea to Japan's justice minister to intervene in the case.

Mr. Fischer won the world chess title in 1972, beating Boris Spassky of the Soviet Union in a victory viewed as a Cold War propaganda coup for the United States.

After his successful 1992 rematch against Mr. Spassky, Bobby Fischer largely dropped out of sight. However, in recent years the eccentric chess genius has become known for his anti-American views and has gone on radio stations in the Philippines praising the September 11 terrorist attacks on the United States. He has also spent considerable time in the last several years in Japan.